By considering various alternatives and by optimising the design, the environmental impact of the project could be minimised. The blocking effect of the structure could be significantly reduced by optimising the design. Thus less compensation dredging was needed.
Enough time should be allotted to developing organisation, contractual strategies and quality systems, to optimise the design and to develop administrative and other procedures.
If possible within the set project requirements, a flexible and adaptable design results in less environmental impact. By adapting the design of the compensation dredging in a late stage of the construction works, on the basis of model computations with the actual geometry, a zero blocking effect could be achieved with no more dredging than necessary.
Environmental research in the pre-construction stage can lead to realistic environmental norms. Estimates of the environmental impacts of construction works led to clear and strict environmental norms, e.g. limits to temporal and spatial extent of exposure to dredging spill.
Clear definition of responsibilities of all actors involved helps to reduce the environmental impact. The contractors, for instance, were quite clear about their responsibility regarding the dredging spill, as a result of which the mean spill limit was never exceeded during the works.
Extensive feedback monitoring during construction in combination with predefined limit values of relevant parameters proved to work well.
All environmental requirements have been met because clear guidelines and goals were set from the outset, and because mutual trust existed between the owner, the consultant and contractor consortia and the environmental authorities.
